class_docstr: MRC Sample class to hold the mrc data info and provide atomic operations.
docstr: Validate whether the sample is legal
  :return: bool
docstr_tok: ["Validate","whether","the","sample","is","legal",":","return",":","bool"]
code: def is_legal(self):
      r"""
      Validate whether the sample is legal
      :return: bool
  
      """
  
      for answer in self.answers:
          answer_text = self.context.text[
              answer["start"] : answer["end"] + 1
          ]
          if answer["text"] != answer_text:
              return False
  
      return True
  
imports: from .cnsample import CnSample
  from ..field import Field, CnTextField
  from ....common.utils.list_op import normalize_scope
  from ....common.preprocess.nltk_res_load import ModelManager
  from ....common.settings import *
  from nltk.stem.lancaster import LancasterStemmer
  from copy import deepcopy
label_desc: Use image node_id 4 for calling the MRCCnSample obj's underlying member method code with example usage: obj.is_legal() and returns: True, False